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Re: Non-linear data selection [message #70996]

Sun, 16 May 2010 06:16

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Gianguido Cianci writes:

>
> On May 15, 7:27 pm, David Fanning <n...@dfanning.com> wrote:
>> aboveIndices = Where((y GE yfit) EQ 1, count)
>
> David, why didn't you use one of the following?
>
> aboveIndices2 = Where(y GE yfit, count)
> aboveIndices3 = Where(y[*] GE yfit[*], count)
>
> I have this vague memory/nightmare that I "need" to do the [*] part in
> order not to get crazy results sometimes (though I can't come up with
> a crazy example right now) so I always use aboveIndices3...
>
> So *are* there differences among these three lines? Cos they all seem
> to work for the example of the original poster. :-|

The second line (aboveIndices2) is what I originally
wrote in my code, but I changed it to give more clues
to the user about what I was doing. (I was too busy working
on my rock garden yesterday to explain myself.)

The third line is totally unnecessary and, at least with
large arrays, will cost you a big memory penalty:

http://www.dfanning.com/misc_tips/submemory.html

But, yes, they should all be equivalent in this case.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Non-linear data selection By: David Fanning on Sun, 16 May 2010 06:16
		Re: Non-linear data selection By: cgguido on Sun, 16 May 2010 00:18
		Re: Non-linear data selection By: Joe Daal on Sat, 15 May 2010 19:18
		Re: Non-linear data selection By: David Fanning on Sat, 15 May 2010 17:27
		Re: Non-linear data selection By: Joe Daal on Sat, 15 May 2010 17:01

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